Chechen leader Ramzan Kadyrov has arrived in the embattled southern Ukrainian city of Mariupol to raise morale among fighters, Russian media reports said Monday.

Chechen fighters have been taking part in Russia's military campaign in pro-Western Ukraine.

Ukraine has said that about 160,000 civilians remain encircled by Russian forces in Mariupol,

Russia said on Monday it was preparing to restrict entry into Russia for nationals of "unfriendly" countries, which include Britain, all EU states and the United States.

"A draft presidential decree is being developed on retaliatory visa measures in response to the 'unfriendly' actions of a number of foreign states," Foreign Minister Sergei Lavrov

Russian billionaire Roman Abramovich and Ukrainian peace negotiators experienced symptoms of a suspected poisoning after a meeting in Kyiv in early March, The Wall Street Journal reported Monday, citing unnamed sources familiar with the matter.

A spokesperson for Abramovich confirmed to the BBC that he had suffered suspected poisoning at peace t